Server rebooted 4 times including a 30 minute off time, just to be sure all the capacitors inside had discharged!

If it were the server the fault should be consistent across all platforms yet it works faultlessly with the laptop? And it works with the pi if the laptop is playing same video. It used to be no problem woth all clients and no config changes or updates on the nas server.

I'll flash a new xbian over the weekend and see if I still get the same problem. I'll use a new SD card this time too..... Fingers crossed!